1. Field of the Invention
The present invention relates to check valves, and, in particular, to inversion resistant check valves.
2. Description of the Prior Art
A check valve is essentially a valve which allows fluid to flow in only one direction through a conduit, while closing and preventing back or reverse flow, when back pressure builds up downstream of the valve to a level greater than the upstream fluid pressure head.
Check valves are used in various fluid transportation operations and must include some means of allowing the forward flow of liquid yet preventing any back flow. Further, it is desirable to have maximum flow at the lowest possible pressure drop in the forward direction of flow, commonly referred to as headloss. It is also necessary to provide some means for resisting collapse under the back pressure or reverse flow of the fluid.
As demonstrated in U.S. Pat. No. 5,769,125 to Duer et al., a check valve may employ a hinge and trough construction, which is an inversion deterrent. Further, as seen in U.S. Pat. No. 5,848,605 to Bailey et al., a spring and poppet mechanism may be utilized to allow forward fluid flow, while, at the same time preventing back flow. Still another example of a check valve with back flow prevention is disclosed in U.S. Pat. No. 5,947,152 to Martin et al. In this patent, a resilient seal ring is used to engage opposed walls of the valve body, allowing forward fluid flow and preventing back flow.
While all of the prior art uses some form of mechanism to prevent back flow, most of the previously mentioned patents are unable to withstand very high back pressure. Further, the prior art that discusses intricate mechanical devices to prevent back flow and inversion are cost prohibitive in many situations. Still further, the prior art, which does provide increased inversion protection, does so at the cost of pressure drop in the forward direction of flow. This headloss degrades the flow pattern and velocity in the valve mechanism, decreasing efficiency.
It is, therefore, an object of this invention to provide a check valve that overcomes the design problems encountered in the prior art. It is another object of this invention to provide high inversion resistance during high back pressure situations, in a much more cost-effective manner. It is also an object of the present invention to allow smooth fluid flow in the forward direction, with little headloss through the valve.
The present invention is a check valve for placement in a fluid conduit including a separator element having at least one opening to allow fluid flow through the separator element. A pliant sealing member is attached to one side of the separator element, covering the separator element opening. This pliant sealing member is configured to deform during forward fluid flow, allowing fluid to pass around the pliant sealing member, and to flatten during reverse fluid flow, covering the opening. In this manner, reverse fluid flow is prevented from entering the opening.
In operation, the fluid flow of liquid enters the check valve area, passes through the opening of the separator element, deflecting the pliant sealing member forward. The fluid passes around the separator element and exits, continuing through the fluid conduit. When back flow is encountered, the pliant sealing member is xe2x80x9cflippedxe2x80x9d backwards, returning to its flat, undeflected state and engaging the separator element. Once in this state, the pliant sealing member effectively blocks the opening in the separator element, preventing passage of liquid in the reverse direction. The invention also includes a method of conveying fluid and preventing reverse fluid flow in a conduit.
The invention itself, both as to its construction and its method of operation, together with additional objects and advantages thereof, will best be understood from the following description of specific embodiments when read in connection with the accompanying drawings.